1. Field of the Invention
The present invention relates to an on-vehicle display system installed in a controllable mobile object, such as a vehicle or the like, and also relates to a display control unit applied thereto (e.g., an ECU).
2. Description of the Related Art
In recent years, an on-vehicle display system has been suggested in which meters and gauges, such as a speedometer, an engine speed indicator, and the like, a navigation picture, and a CCD image are displayed on a display panel included in an instrument panel of an automobile or the like.
In such an on-vehicle display system, it is especially demanded that important vehicle information such as meters and gauges, such as a speedometer, an engine speed indicator, and the like be stably displayed. That is, even if a portion of what is related to electronics in a vehicle malfunctions, such important vehicle information as mentioned above needs to be still displayed so as to secure the safety of driving.
Japanese Patent Application Publication, Tokukai, No. 2005-221664 discloses a vehicle multi-monitor system including a plurality of displays, the vehicle multi-monitor system being capable of still displaying important information even if any of the displays malfunctions. This is shown in FIG. 10.
The vehicle multi-monitor system disclosed in FIG. 10 operates as below. That is, in a case where something abnormal occurs in a display 103 when the display 103 and a display 102 are in charge of displaying a meter and displaying a car navigation system, respectively, an on-vehicle server 101 detects the abnormality by self-examining data from the display 103 or the fact that the on-vehicle server 101 does not receive the self-examining data from the display 103 even after a predetermined time has elapsed. When the abnormality is detected, the on-vehicle server 101 changes the executors of applications (a meter AP 115 and/or a car navigation system AP 116). That is, in this case, the abnormality occurs in the display 103 that displays the meter. The meter displayed on the display 103 is comparatively more important for a driver than the car navigation system displayed on the display 102. Therefore, the meter AP 115 is distributed to the display 102 that operates normally. Then, the display 102 displays the meter AP 115.
In this way, when the abnormality occurs in the display for displaying specific information, the display which displayed information whose priority is lower than the specific information displays the specific information, thereby to avoid the situation where the information important for the driver is not displayed.
However, with the configuration described in Japanese Patent Application Publication, Tokukai, No. 2005-221664, meters (pieces of important information) which are supposed to be displayed in a liquid crystal monitor 131 are displayed in a liquid crystal monitor 121 for the car navigation system. That is, a location where the meters important for the driver are displayed is changed and the safety of driving may thus be affected. Furthermore, the configuration of FIG. 10 consequently makes it impossible to display the car navigation system, thereby to force the driver to suffer inconvenience as well.